Pb-acid storage batteries, among others, generate gases during cycling. These gases are vented from the battery innards to the ambient via venting systems designed to permit gas passage but inhibit the outflow of electrolyte (i.e., from innards to ambient) therethrough. The trapped electrolyte is then drained back into the battery cells from whence it came.
There are essentially two types of battery venting systems commonly in use. These types can be classified as either vertical-type or horizontal-type depending on the orientation of the chamber used to trap the electrolyte. In this regard, both types typically include an electrolye trapping chamber which is located between a vent/drainage aperture that leads to the battery's electrochemical innards (i.e., plates, electrodes, separators, etc.) and an exhaust port which leads to the atmosphere. The venting/drainage aperture usually passes through the floor of the electrolyte trapping chamber and is sized to allow gas passage while minimizing entry of electrolyte splash into the trapping chamber. Nonetheless, the trapping chambers are commonly invaded by electrolyte passing up through the venting/drainage aperture as a result of excessive overcharging, sloshing, splashing, etc. (i.e., due to mishandling, vibration, tilting, or the like).
To substantially prevent electrolyte from exiting the battery, trapping chambers are typically equipped with a variety of baffles or the like to inhibit electrolyte mobility and substantially prevent its reaching the exhaust port and escaping to the ambient. Sloping chamber floors are typically used to facilitate draining back (i.e., refluxing) of the electrolyte into the cell through the same aperture from whence it came.
Discrete vent plugs found on many batteries exemplify vertical-type vent systems. The plugs typically include a deep, cylindrical chamber which fits tightly into the filler well of the battery. Separation of the electrolyte from the gas occurs primarily by gravity as the gases rise vertically through the cylindrical chamber and the heavier electrolyte falls to the chamber floor. The floor of the chamber slopes toward a central aperture through which the gases can pass upwardly and the electrolyte can drain back into the cell. The top of the chamber has an exhaust port for discharging the gases to the atmosphere. The chamber may also contain a variety of internal baffles to prevent electrolyte from reaching the exhaust port.
Horizontal-type vent systems, on the other hand, are most frequently formed integrally with the battery cover and typically include an elongated chamber extending horizontally across at least part of the top of the battery. The vent/drainage aperture is usually located laterally and elevationally remote from the exhaust port, and the gases passing through the vent/drainage aperture horizontally traverse much of the length of the chamber before discharge to the ambient. Such designs frequently employ a manifolding arrangement whereby several trapping chambers share a single exhaust port. One such horizontal-type system is disclosed in my copending U.S. patent application Ser. No. 305,096, which was filed on Sept. 24, 1981 and is assigned to the assignee of the present invention.
Horizontal-type venting systems are generally more susceptible to electrolyte leakage than vertical systems. In this regard, the substantial loss of the benefits of gravity, the wettability of the surfaces defining the electrolyte-trapping chamber, and the ability of the electrolyte to move more readily through horizontal chambers (i.e., incident to vibration, jostling and surface tension affects) substantially increase the risk of electrolyte reaching and escaping the exhaust port. In order to minimize this leakage, the trapping chambers have been made relatively deep and thereby add non-productive height to the battery. Unnecessarily tall SLI batteries are particularly undesirable in modern times where the trend toward smaller vehicles dictates the need for smaller batteries. Likewise more leak proof SLI batteries are desirable not only to conserve electrolyte and prevent corrosion of vehicular parts, but also to permit location of the battery in a vehicle at sites not readily available for convenient battery maintenance.
It is an object of the present invention to provide a low-silhouette, horizontal-type venting system having manifestly improved electrolyte trapping and refluxing characteristics. This and other objects and advantages of the present invention will become more readily apparent from the detailed description thereof which follows.